From: Bob Blick <bobblick@outlook.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Thu, 30 Jul 2020 09:26:25 -0700
Subject: [PIC] Simple GCC question
Thread-Topic: [PIC] Simple GCC question
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I'm using a nice little HD44780 LCD library in an STM32 project, it works g=
reat but I'm stuck with a variable scope problem that I can only seem to ma=
ke worse because GCC is a bit stricter than I want it to be at this point. =
Sorry if the code example doesn't wordwrap properly.

If, somewhere in main() I create an instance of the LCD like this:
  Lcd_PortType ports[] =3D {LCD_D4_GPIO_Port, LCD_D5_GPIO_Port, LCD_D6_GPIO=
_Port, LCD_D7_GPIO_Port};
  Lcd_PinType pins[] =3D {LCD_D4_Pin, LCD_D5_Pin, LCD_D6_Pin, LCD_D7_Pin};
  Lcd_HandleTypeDef lcd =3D Lcd_create(ports, pins, LCD_RS_GPIO_Port, LCD_R=
S_Pin, LCD_EN_GPIO_Port, LCD_EN_Pin, LCD_4_BIT_MODE);

then I can use it like this:
  Lcd_cursor(&lcd, 1,6);

but of course I can't do that from within another function since "lcd" only=
 exists in main()

If I try to make it all global by creating lcd outside of main(), GCC doesn=
't like that because initializer elements must be constants and it doesn't =
consider "ports" and "pins" to be constants.

Not being a real C programmer this has stopped me in my tracks. If I was st=
uck on a deserted island I would use this library as a basis for something =
with ports and pins hardcoded, but I'm hoping a real expert would give me s=
ome gentle help, which will certainly educate me about doing things the cor=
rect way and also get me past this little hurdle.

Thanks, Bob
--=20
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